Power supply for plural logic cards



May 26, 1970 s, LEVIN ETAL POWER SUPPLY FOR PLURAL LOGIC CARDS Filed Nov. 22, 1967 NORTON s LEV/N 400 o. muoy BY R0 (2, ,4 A/

INVENTORS xwisuosu QQSQ QBQ ATTO R N EY United States Patent 3,514,691 POWER SUPPLY FOR PLURAL LOGIC CARDS Morton S. Levin, Woodclilf Lake, and James Q. Maloy, Wayne, N.J., assignors to Datascan Incorporated, Clifton, N.J., a corporation of New Jersey Filed Nov. 22, 1967, Ser. No. 685,159 Int. Cl. Gf 1/58, 1/64 U.S. Cl. 3239 '12 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to electrical circuits and more particularly to a power supply for integrated circuit logic cards.

It is extremely important that the power supply for a logic circuitry box of the type used for automatic test systems, digital control, computer interlays and the like, be free from transients, spikes, and variations in voltage.

Heretofore power supplies have been provided in which a master regulator is incorporated, the regulated voltage being supplied to individual logic cards through distribution busses. Difiiculty has been had with such systems because of interaction noise transmitted through the distribution busses. Attempts have been made to overcome this problem by the use of filter networks. However, such circuits have not been wholly satisfactory because of the high distribution bus impedance.

The present invention aims to overcome the difliculties and disadvantages of prior power supplies for logic circuitry by providing a power supply in which a main regulated power supply of not exceptionally high quality is provided. An extremely well regulated reference voltage is established from the main power supply and used to regulate the main power supply and also to regulate a small auxiliary power supply for each of the logic cards.

The logic card power supply in accordance with the invention is advantageous in that spikes in the power supply are greatly reduced.

Objects and advantages of the invention will be appar ent from the following description and from the accompanying drawing which shows, by way of example, an embodiment of the invention.

Referring to the drawing a sixty cycle alternating current supply of about one hundred and fifteen volts is adapted to be connected to the primary of transformer T1 through a protective fuse F1. The secondary of the transformer T1 is center tapped and grounded.

The transformer T1 output is full wave rectified by diodes CR5 and CR6 and filtered by capacitor C6. The output of capacitor C6 feeds pass transistor Q11 through a current limiting resistor R27. This limiting resistor R27 is also used in the short circuit protection system which is comprised of diode CR1, resistors R1, R2, R3, R4 and transistors Q1 and Q10. When an overcurrent is detected transistor Q1 is turned on by the voltage drop across resistor R27 and turns on transistor Q which pulls the base of transistor Q2 toward ground which in turn pulls the base of the transistor Q11 toward ground reducing the direct current output voltage. Transistor Q2 is normally used as a current amplifier driving pass transistor Q11. The drive for transistor Q2 is controlled by transistor Q4 which is one half of a differential amplifier comprised of transistors Q3 and Q4 and in which transistor Q3 is driven by the power supply reference voltage derived from Zener CR3. Transistor Q4 senses the output voltage in divider string R9, R10 and R23. R23 is a potentiometer used to set a seven volt direct current voltage level. Resistor R7 is a dissipation limiting collector load for transistor Q3. Resistor R25 provides a leakage path for the transistor Q11. Resistor R8 is a common emitter resistor for the transistor Q3Q4 differential amplifier combination. Transistors Q2, Q3 and Q4 form a power supply regulator. Transistors Q1 and Q10 form a current limiting network. Diode CR1 is used as a stand off diode in the current limiting detector network. Capacitor C1 is a filter capacitor which allows heavy transient currents to be pulled through the pass transistor Q11 without the current limiting network coming into operation. Transistor Q5 and silicon controlled rectifier SC-Rl and Zener diode CR2 are part of an overvoltage protection network sensed by Zener CR2. Resistor R12 is the base resistor for transistor Q5. Resistor R11 is a collector load for transistor Q5. When Zener CR2 passes a potential transistor Q5 is turned on, turning on the silicon controlled rectifier SCRl which clamps the plus seven volt feed.

Thus it may be seen that the high current power supply need only be a semiregulated economical power supply which is used as the input voltage for a 5.6 volt power supply.

Transistors Q6 and Q7 function in exactly the same Way as transistors Q3 and Q4 in the 7 volt power supply, that is they form a differential amplifier in which the reference voltage is fed into the base of transistor Q6 and the power supply output voltage is sensed by the base of transistor Q7 in the output voltage divider R24. Resistor R16 is the common emitter resistor for the differential amplifier. Resistor R17 is the collector load for transistor Q7. Capacitor C4 is a high frequency filter capacitor placed across the sensed voltage. Resistor R20 is used to sense the current in the 5.6 volt power supply and diodes CR4, resistors R19, R21 and R22 and transistor Q8 make up a current sensing network which is used to clamp the output of the 5.6 volt power supply in the same manner as described for the 7 volt supply. Transistor Q9 is the output pass transistor for the plus 5.6 volt power supply and is driven directly from the collector of transistor Q7. The output of the 5.6 volt power supply is further filtered by capacitor C5.

Since the 5.6 volt highly regulated power supply need only furnish a small amount of current (one twentieth of the output current of the 7 volt power supply) it may be made a highly regulated power supply at relatively low cost. Zener diode CR3 is the reference for both power supplies.

The output of the 7 volt supply is passed to transistor Q12 connected as a cathode follower. Resistor R30 is for current limiting purposes in the event of circuit breakdown. Resistor R31 and capacitor C10 form an input filter for the 5.6 volt supply. Capacitor C11 is an output filter passing high frequency.

Resistors R30, R31, capacitors C10, C11 and transistor Q12 are positioned on a logic card 32 conveniently spaced a distance from the remainder of the power supply system. Across the output of the regulated power supply for the logic card 32 is provided a pair of output terminals 33 and 34 adapted to be connected to logic card circuitry which may be positioned in the area indicated by the numeral 35. A second logic card is identified by the numeral 36. Additional logic cards may be added as desired, the circuitry thereon including the power supply unit R30, R31, capacitors C10, C11 and transistor Q12, each of which has output terminals 33 and 34 for connection to logic card circuitry as indicated at 35.

The 5 volt output of the dynamic decoupling circuit has less than 5 millivolt peak to peak noise under the worst operating conditions and for a 100 milliampere change in current the maximum ripple is approximately 5 :millivolt. The 7 volt supply is about 2 percent supply (plus or minus 140 millivolt). The 5.6 volt power supply is about a two tenths percent power supply (plus or minus millivolt).

Thus it will be seen that the power supply in accord ance with the invention permits the use of a relatively noisy basic power supply and still have a quiet power supply for the logic cards.

While the invention has been described and illustrated with reference to a specific embodiment thereof, it will be understood that other embodiments may be resorted to without departing from the invention. Therefore, the form of the invention set out above should be considered as illustrative and not as limiting the scope of the following claims.

We claim:

1. A power supply system for a plurality of logic cards, the system comprising a power supply unit including means providing a source of direct current energy, means providing a low quality regulated power supply fed by said direct current source, means providing a well-regulated reference voltage supply fed by said low quality regulated supply, a plurality of logic cards, said power supply unit feeding out to each of said logic cards a low quality direct current supply and a high quality direct current regulated supply, a logic card voltage regulator carried by each logic card, each of said logic card voltage regualtors supplied by said low quality regulated power supply and controll 'by said well-regulated reference voltage, a regulator output carried by each logic card, the regulator outputs adapted to be connected to logic card circuitry, and a filter also positioned on each logic card and connected to its high quality regulated supply, whereby the output of each logic card voltage regulator is a, highly regulated low ripple supply substantially unaffected by possible noise.

2. A direct current power supply system according to claim 1 in which said means providing a low quality regulated power supply is a pass transistor.

3. A direct current power supply system according to claim 1 in which said logic card regulator is a cathode follower.

4. A direct current power supply system according to claim 1 in which short circuit protection means is included comprising potential dropping means connected in series with said means providing a low quality power supply, and control means for said power supply responsive to greater than normal potential drop across said potential dropping means.

5. A direct current power supply system according to claim 4 in which capacitor means is included to supply heavy transients drawn by said low quality power supply.

6. A direct current power supply system according to claim 4 in which overvoltage means is included including a silicon controlled rectifier connected across said source of direct current outwardly of said potential dropping means, and control means is provided for said silicon controlled rectifier.

7. A direct current power supply system according to claim 1 in which said low quality regulated power supply is a pass transistor, and in which said means providing a well regulated reference voltage is a Zener diode controlling a differential amplifier in which one half of said amplifier is driven by the Zener diode and the other half of said amplifier is driven by a voltage derived from the output voltage.

8. A direct current power supply system according to claim 1 in which said means providing a well regulated reference voltage is a Zener diode controlling a differential amplifier in which one half of said amplifier is driven by the Zener diode and the other half of said amplifier is driven by a voltage derived from the output voltage, and in which said logic card voltage regulator is a cathode follower.

9. A direct current power supply system according to claim 1 in which said low quality regulated power supply is a pass transistor, said means providing a well regulated reference voltage is a Zener diode controlling a differential amplifier in which one half of said amplifier is driven by the Zener diode and the other half of said amplifier is driven by a voltage derived from the output voltage, said logic card voltage regulator is a cathode follower, in which short circuit protection means is included comprising potential dropping means connected in series with said power supply and control means for said power supply responsive to greater than normal potential drop across said potential dropping means, in which capacitor means is included to supply heavy transients drawn by said power supply, and in which overvoltage means is included including a silicon controlled rectifier connected across said source of direct current outwardly of said potential dropping means, and control means is provided for said silicon controlled rectifier.

10. A direct current power supply system according to claim 1 in which a current limiting resistor is provided positioned on said logic card and connected between said low quality regulated power supply and said regulator.

11. A direct current power supply system according to claim 1 in which said filter includes a resistance connected in series between said high quality regulated power supply and said regulator and a capacitor is provided connected between the junction of said resistor and said regulator and ground.

12. A direct current power supply system according to claim 1 in which said regulator is a transistor connected as a cathode follower, a filter capacitor is provided and connected between the transistor emitter and ground, and a pair of terminals are provided connected across said filter capacitor thereby providing said regulator output adapted to be connected to logic card circuitry.

References Cited UNITED STATES PATENTS 3,049,632v 8/ 1962 Staples. 3,068,392 12/1962 Santelmann 32118 3,163,814 12/1964 Todd. 3,260,920 7/ 1966 Shoemaker 32l-18 3,359,434 12/ 1967 Galluzzi. 3,391,330 7/ 1968 Grossoehme 323--9 J. D. MILLER, Primary Examiner A. D. PELLINEN, Assistant Examiner US. 01. X.R. 

